#include <iostream>

using namespace std;

class Box{
    public:
    //无参的构造函数
    // Box(){
    //     cout << "Box()" << endl;
    //     _length=10;
    //     _width=10;
    //     _height=10;
    // }
    //有参的构造函数
    Box(int length, int width, int height):p(_length),sum(1000){
        cout << "Box(int length, int width, int height)" << endl;
        _length=length;
        _width=width;
        _height=height;
    }

    Box():_length(10),_width(10),_height(10),p(_length),sum(1000){
        cout << "Box()" << endl;
    }

    private:
        int _length;
        int _width;
        int _height;
        int& p;
        const int sum;
};

int main(){
    Box a;
    //Box a,b;
    //Box box[4];
    //Box b1(20,10,10);
    return 0;
}